1. Field of the Invention
The present invention relates to the field of fertilizer production, and more particularly to a fertilizer including biosolids, and calcium sulfate dihydrate.
2. Description of Related Art
As can be seen by reference to the following U.S. Pat. Nos. 3,979,199; 5,158,594; 7,175,683; 8,062,405; 8,075,659; 8,241,389; and 8,25,648, the prior art is replete with myriad and diverse fertilizers.
As can be seen in U.S. Pat. No. 3,979,199, pulverized phosphate rock can be spread onto, or mixed into soil which is to be fertilized. The soil is then treated with a solution of sulfurous acid, usually the output of a device which burns sulfur in air to form sulfur dioxide and then dissolves the sulfur dioxide in water. The water may be irrigation water which thereupon both irrigates the soil and reacts with the phosphate rock to fertilize the soil. Common phosphate ores include a substantial amount of calcium, with which and with oxygen, the sulfurous acid reacts to form gypsum (calcium sulfate). Gypsum is a widely-used corrective substance applied to croplands, and the gypsum formed by this treatment reduces the requirement to purchase gypsum as a product separate from the fertilizer. Substantially, all of the phosphorus contained in the rock can ultimately be solubilized as “available phosphate” with the use of this method.
Further as seen in U.S. Pat. No. 5,158,594, this patent teaches the process for converting phosphor-gypsum waste product from the wet process of manufacturing phosphoric acid from phosphate rock by ammoniating said product at a pH of 6.5 or less and adjusting the phosphorus and potassium values of said ammoniated product by addition of one or more sources of potassium and phosphorus.
U.S. Pat. No. 7,175,683, teaches a process for transforming sludge into NPK type granulated fertilizer in which the energy consumed is reduced 90% by the addition of a special filtration step. In that step, the water content is reduced 50%, and the remaining water is evaporated by the exothermic reaction occurring in the process. This process includes mechanisms that allow some of the by-products generated by some of the reactions such as gypsum, to adsorb crystallization water, thereby reducing the humidity of the mass without using external energy.
U.S. Pat. No. 8,062,405 is a value added granulated organic fertilizer produced from poultry litter and biosolids using agglomeration techniques with a pin mixer. The granulated organic fertilizer includes granules of biosolids, a nitrification inhibitor, such as dicyandiamide, and a binding agent, such as lignosulfonate, urea formaldehyde, or water. The nitrogen concentration of the granulated organic fertilizer is increased by being fortified with urea. The poultry litter and biosolids formulated into the granulated organic fertilizer aid in flowability, storage, and spreading, while value added plant nutrient ingredients provide an environmentally safer fertilizer than fresh poultry litter, municipal biosolids and/or many commercially available products commonly used in urban and agricultural systems. The binding agents change the fertilizer granule water soluble phosphorus and nitrogen concentrations and reduce fines and dust. The nitrification inhibitor reduces nitrogen losses via leaching and dentrification, while biosolids decrease water soluble and total phosphorus concentrations in runoff water for environment protection.
Further, as referenced in U.S. Pat. No. 8,075,659, preparations with improved urease-inhibitory effect which comprise at least two different (thio)phosphoric triamides and to urea-comprising fertilizers which comprise these preparations are taught. Furthermore, a method of preparing these preparations, to the use of these preparations in the fertilization with urea-comprising fertilizers, and to the use of urea-comprising fertilizers which comprise these preparations in agriculture or in horticulture are taught.
U.S. Pat. No. 8,241,389 relates to a method and a device for producing nitrogen fertilizer, removing phosphate from organic waste products in liquid phase, sanitizing said waste or reducing emissions, and limiting the potassium concentration. The waste product is heated to temperatures ranging between 40° C. at a subatmospheric pressure. The escaping gas that contains carbon dioxide and ammonia is contacted with a mineral aqueous suspension, then the excess gas is conducted within the circuit while the subatmospheric pressure is autogenously stabilized. Then the formed nitrogen fertilizer is discharged. In order to additionally produce phosphate fertilizer and limit the potassium concentration, the obtained fertilizer product is divided into the liquid and solid portion. All or some of the solid portion is redirected into the stripping receptacle while the liquid waste product that is stripped of nitrogen and compounds and phosphorus compounds is cooled and mixed with at least one sulfate containing compound to limit the small amount of a basic mineral powder is added thereto. The last solid portion obtained from the treatment can be used directly as phosphate fertilizer, potassium fertilizer, or phosphate containing and potassium containing mixed fertilizer.
Finally, U.S. Pat. No. 8,425,648 describes a slow calcium release fertilizer and methods for their synthesis. Organic materials, particularly from manure, are used for coating to achieve slow release forms of fertilizer. It is desirable to use low temperature kinetic treatments to prepare pulverized forms having small size, yet well coated with natural (non-denature) molecular material to achieve the slow release. Kinetic processing of rock gypsum and manure at low temperatures with added acid is a desired embodiment. Use of fertilizers leads to acceleration of microbial viability.
Particularly within the mid-Atlantic states, as a result of Chesapeake Bay water quality concerns, there is a great deal of environmental regulation with regards to agricultural nutrients. For many years, the primary concern was nitrogen runoff as it is easily water soluble and that which is not taken up by a crop can percolate to groundwater or runoff to surface waters. Nutrient management plans and specific application rates address this particular matter and there is typically no soil residual from year to year aside from that which must be broken down in organic matter decomposition. Of primary concern to commercial agriculture at this time is soil phosphorus. In the 1980's, the research of the time and overall soil phosphorus levels recommended adding at least that phosphorus which was required for plant uptake, but that amounts over these values was fine as it basically went into a “soil bank” whereby it would be available as needed. Unlike nitrogen application, phosphorus is typically bound tightly in the soil matrix and not free to travel off-site or into the groundwater. At the time phosphorus water pollution was strictly limited to reducing soil runoff as phosphorus would contaminate waterways if it was attached to the soil particles. Over many years of addition of larger than desirable phosphorus amounts to soils there is an overabundance of that nutrient. At high levels, the phosphorus is not as tightly held and that which is readily available and taken up by the plant may, by being water soluble, enter ground and surface waters. Nutrient management plans now take phosphorus addition and soil phosphorus background levels and with the above statement in mind, products such as manures and biosolids become phosphorus limiting up to and including no application allowed. In other words, to supply the required nitrogen with a given product, too much phosphorus would be added to the soil thereby precluding application. Biosolids and animal manures are particularly of issue with regards to this statement, and yet, as they are produced, they must be used in the existing and natural state.
While all of the aforementioned prior art inventions are adequate for the basic purpose and function for which they have been specifically designed, they are uniformly deficient with respect to their failure to provide a simple, efficient, and practical way to provide an inexpensive fertilizer including biosolids with inexpensive materials that limits phosphorous availability.
As a consequence of the foregoing situation, there has existed a longstanding need for a new and improved fertilizer using biosolids and gypsum and/or other phosphorus binding agents, such as iron or aluminum chemicals or byproducts with elevated levels of iron and aluminum.